The present invention relates to a system and method for supporting communications services on behalf of a communications device which cannot provide those services itself. More specifically, the present invention relates to a system and method for supporting foreign terminals in a communications network.
In the developing field of IP telephony, there are a multitude of network architecture designs and implementations to consider. The ultimate goal, from a subscriber standpoint, is to provide an IP telephony system that does not require the subscriber to alter the way they perform existing tasks such as placing and receiving calls, and does not affect the set of calling services (caller ID, call forwarding, etc.) that the subscriber may have subscribed to. That is, any new IP telephony system should operate such that subscribers do not have to learn new means for accessing and using services they have always used from their traditional phones should those phones be so called xe2x80x9cdumbxe2x80x9d terminals.
IP telephony protocols, and there are several under industry-wide consideration, and existing telephony protocols are quite different due to the fact that each handles voice and/or data signals differently. The chief difference is that an IP network partitions a voice and/or data signal into packets and relays the packets over the network from point to point. The packets are then re-arranged at the endpoint for distribution to the consumer in a usable form. Most existing telephony networks are analog in nature meaning signals are not broken into digital packets.
Moreover, IP telephony networks and existing telephony networks must be made compatible with one another in order to allow an IP telephony subscriber to communicate with a non-IP telephony subscriber and vice-versa. This necessitates network interfaces capable of converting between IP standards and protocols and existing standards and protocols.
Existing telephony networks have an advantage over IP telephony networks in that extensive call processing network hardware is already in place. Moreover, calling services have been developed to operate within existing telephone architecture. Thus, it makes sense to develop an IP telephony system that can utilize to the greatest extent possible the existing network architecture. This primarily entails upgrading certain existing hardware with the previously mentioned network interfaces capable of converting between IP standards and protocols and existing standards and protocols. Another option is to create standalone network interface devices that perform protocol conversion. Such devices would then augment existing architecture. It is to be understood that some of the protocol conversion between IP telephony and existing telephony can be achieved via software. That is, a 100% hardware solution is not required.
As mentioned before, an IP telephony subscriber may want to access the same calling services as existing telephony subscribers. There are a multitude of such services that are currently offered by telephony service providers. These services all require some form of call processing logic to achieve their stated goal. Some services require more extensive processing than others and therefore are network based meaning that the processing logic is performed in a device or node within the telephone network and not by the phone or terminal itself. Other less computationally intensive services may be by the consumer""s own terminal (phone). Additionally, some terminals are xe2x80x9csmarterxe2x80x9d than others in that they possess greater processing ability and can, therefore, perform certain services themselves as opposed to relying on the network. The table below provides a sampling of calling services and the location at which they may be performed, that is whether the service is network or terminal based. The following table is exemplary, not exhaustive.
New IP telephony networks define interfaces between a terminal (or client) and a network which necessitate a computationally powerful terminal. The terminal must be capable of managing its call state, providing supplementary services, and managing bearer connections, etc. All of these responsibilities require computational processing capacity (hardware) and software logic. Large numbers of terminals will likely be installed into a network which is expensive in terms of hardware. It is possible to create less computationally intense, less expensive terminals. However, the responsibilities of these scaled back terminals still must be supported. The present invention provides for the delegation of certain terminal responsibilities to a server residing on a network. Thus, use can be made of less expensive, less computationally intensive terminals in an IP telephony network.
The present invention is to be distinguished from IP PBX systems and xe2x80x9cblack boxxe2x80x9d devices which allow analog phones to be connected to digital PBX systems. The key difference between a terminal proxy as disclosed by the present invention and an IP PBX controller is that the terminal proxy is not a network call processing engine, rather it is a remote implementation of local call processing. The terminal proxy makes a terminal look like a terminal of another type from the perspective of the IP PBX controller or the central office. The key differentiation with respect to the black boxes which permit analog phones to be connected to digital PBXs is that the black box processes the media and is physically between the PBX and the phone. The terminal proxy, in contrast, is a signaling translator which is not physically between the two machines, only logically so.
The present invention applies traditional telephony architecture and design to an IP telephony network. To date, thin client (simple terminal) solutions have not been proposed for IP telephony, except in such a way as would eliminate service capabilities or bundle them in a network server such as, for instance, an IP PBX controller.
A terminal according to the present invention is designed to identify its supporting server upon initialization. Henceforth, the terminal provides each user input stimulus to that server (or its backup) and responds to stimulus from the server via a network interface to an IP network using, for instance, the NORTEL proprietary universal stimulus IP protocol (hereinafter xe2x80x9cUNISTIM IPxe2x80x9d). The server is then responsible for managing the state machine of the client, providing local or terminal specific supplementary services, and meeting protocol requirements for, inter afia, the network interface, SIP, or H.323.
The present invention thus comprises at least one terminal coupled to an IP network and a terminal proxy coupled to the IP network and communicable with the terminals. The terminal proxy communicates with and manages the call processing logic for terminals which cannot perform such tasks for themselves. The present invention further comprises a network interface situated between the terminals and the IP network interface for ensuring that all call control functional signaling between the IP network and the terminals are in a compatible format. The present invention still further comprises a terminal adapter coupled to the IP network via the network interface and supports terminals that do not communicate in an IP protocol. The terminal adapter receives the call control protocol of the terminal and converts it into an IP protocol usable by the IP network.